Shapes, multiple twins and surface structures of monodisperse FePt magnetic nanocrystals

Shapes, surface atomic arrangement and structural evolution induced by annealing of monodisperse FePt nanocrystals, synthesized by a solution phase chemical procedure, have been studied by high-resolution transmission electron microscopy. The as-synthesized FePt nanocrystals display dominantly a truncated octahedron shape enclosed by flat {100}, stepped {111} and zig-zag {110} facets. The Marks decahedron FePt nanocrystals and the icosahedron based multiply twined FePt nanocrystals are identified in the as-synthesized particles. An improved structural model has been proposed for the multiply twined nanocrystals. After annealing, the {110} facets disappear and a regular cuboctahedron becomes the dominant shape. Surfaces of the FePt nanocrystals show no reconstruction but with some atomic steps and kinks. (C) 2002 Elsevier Science B.V. All rights reserved.